Publications


Radio Galaxy Zoo: Discovery of a poor cluster through a giant wide-angle tail radio galaxy

Monthly Notices of the Royal Astronomical Society 460 (2016) 2376-2384

JK Banfield, H Andernach, AD Kapińska, L Rudnick, MJ Hardcastle, G Cotter, S Vaughan, TW Jones, I Heywood, JD Wing, OI Wong, T Matorny, IA Terentev, R López-Sánchez, RP Norris, N Seymour, SS Shabala, KW Willett

© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.We have discovered a previously unreported poor cluster of galaxies (RGZ-CL J0823.2+0333) through an unusual giant wide-angle tail radio galaxy found in the Radio Galaxy Zoo project. We obtained a spectroscopic redshift of z = 0.0897 for the E0-type host galaxy, 2MASX J08231289+0333016, leading to Mr = -22.6 and a 1.4 GHz radio luminosity density of L1.4 = 5.5 × 1024 W Hz-1. These radio and optical luminosities are typical for wide-angle tailed radio galaxies near the borderline between Fanaroff-Riley classes I and II. The projected largest angular size of ≈8 arcmin corresponds to 800 kpc and the full length of the source along the curved jets/trails is 1.1 Mpc in projection. X-ray data from the XMM-Newton archive yield an upper limit on the X-ray luminosity of the thermal emission surrounding RGZ J082312.9+033301 at 1.2-2.6 × 1043 erg s-1 for assumed intracluster medium temperatures of 1.0-5.0 keV. Our analysis of the environment surrounding RGZ J082312.9+033301 indicates that RGZ J082312.9+033301 lies within a poor cluster. The observed radio morphology suggests that (a) the host galaxy is moving at a significant velocity with respect to an ambient medium like that of at least a poor cluster, and that (b) the source may have had two ignition events of the active galactic nucleus with 107 yr in between. This reinforces the idea that an association between RGZ J082312.9+033301 and the newly discovered poor cluster exists.


Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2016) ARTN 037

MG Aartsen, K Abraham, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, D Altmann, T Anderson, I Ansseau, M Archinger, C Arguelles, TC Arlen, J Auffenberg, X Bai, SW Barwick, V Baum, R Bay, JJ Beatty, JB Tjus, K-H Becker, E Beiser, P Berghaus, D Berley, E Bernardini, A Bernhard, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, C Bohm, M Boerner, F Bos, D Bose, S Boeser, O Botner, J Braun, L Brayeur, H-P Bretz, N Buzinsky, J Casey, M Casier, E Cheung, D Chirkin, A Christov, K Clark, L Classen, S Coenders, DF Cowen, AHC Silva, J Daughhetee, JC Davis, M Day, JPAM de Andre, C De Clercq, EDP Rosendo, H Dembinski, S De Ridder, P Desiati, KD de Vries, G de Wasseige, M de With, T DeYoung, JC Diaz-Velez, V di Lorenzo, JP Dumm, M Dunkman, B Eberhardt, T Ehrhardt, B Eichmann, S Euler, PA Evenson, S Fahey, AR Fazely, J Feintzeig, J Felde, K Filimonov, C Finley, T Fischer-Wasels, S Flis, C-C Foesig, T Fuchs, TK Gaisser, R Gaior, J Gallagher, L Gerhardt, K Ghorbani, D Gier, L Gladstone, M Glagla, T Gluesenkamp, A Goldschmidt, G Golup, JG Gonzalez, D Gora, D Grant, Z Griffith, A Gross, C Ha, C Haack, AH Ismail, A Hallgren, F Halzen, E Hansen, B Hansmann, K Hanson, D Hebecker, D Heereman, K Helbing, R Hellauer, S Hickford, J Hignight, GC Hill, KD Hoffman, R Hoffmann, K Holzapfel, A Homeier, K Hoshina, F Huang, M Huber, W Huelsnitz, PO Hulth, K Hultqvist, S In, A Ishihara, E Jacobi, GS Japaridze, M Jeong, K Jero, M Jurkovic, A Kappes, T Karg, A Karle, M Kauer, A Keivani, JL Kelley, J Kemp, A Kheirandish, J Kiryluk, J Klaes, SR Klein, G Kohnen, R Koirala, H Kolanoski, R Konietz, L Koepke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, K Krings, G Kroll, M Kroll, G Krueckl, J Kunnen, N Kurahashi, T Kuwabara, M Labare, JL Lanfranchi, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leuner, L Lu, J Luenemann, J Madsen, G Maggi, KBM Mahn, M Mandelartz, R Maruyama, K Mase, HS Matis, R Maunu, F McNally, K Meagher, M Medici, A Meli, T Menne, G Merino, T Meures, S Miarecki, E Middell, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, G Neer, H Niederhausen, SC Nowicki, DR Nygren, AO Pollmann, A Olivas, A Omairat, A O'Murchadha, T Palczewski, H Pandya, DV Pankova, L Paul, JA Pepper, CP de Los Heros, C Pfendner, D Pieloth, E Pinat, J Posselt, PB Price, GT Przybylski, M Quinnan, C Raab, L Raedel, M Rameez, K Rawlins, R Reimann, M Relich, E Resconi, W Rhode, M Richman, S Richter, B Riedel, S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, L Sabbatini, H-G Sander, A Sandrock, J Sandroos, S Sarkar, K Schatto, M Schimp, T Schmidt, S Schoenen, S Schoeneberg, A Schoenwald, L Schulte, L Schumacher, D Seckel, S Seunarine, D Soldin, M Song, GM Spiczak, C Spiering, M Stahlberg, M Stamatikos, T Stanev, A Stasik, A Steuer, T Stezelberger, RG Stokstad, A Stoessl, R Stroem, NL Strotjohann, GW Sullivan, M Sutherland, H Taavola, I Taboada, J Tatar, S Ter-Antonyan, A Terliuk, G Tesic, S Tilav, PA Toale, MN Tobin, S Toscano, D Tosi, M Tselengidou, A Turcati, E Unger, M Usner, S Vallecorsa, J Vandenbroucke, N van Eijndhoven, S Vanheule, J van Santen, J Veenkamp, M Vehring, M Voge, M Vraeghe, C Walck, A Wallace, M Wallraff, N Wandkowsky, C Weaver, C Wendt, S Westerhoff, BJ Whelan, K Wiebe, CH Wiebusch, L Wille, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, M Zoll, A Aab, P Abreu, M Aglietta, EJ Ahn, I Al Samarai, IFM Albuquerque, I Allekotte, P Allison, A Almela, JA Castillo, J Alvarez-Muniz, RA Batista, M Ambrosio, A Aminaei, L Anchordoqui, B Andrada, S Andringa, C Aramo, F Arqueros, N Arsene, H Asorey, P Assis, J Aublin, G Avila, N Awal, AM Badescu, C Baus, JJ Beatty, KH Becker, JA Bellido, C Berat, ME Bertaina, X Bertou, PL Biermann, P Billoir, SG Blaess, A Blanco, M Blanco, J Blazek, C Bleve, H Bluemer, M Bohacova, D Boncioli, C Bonifazi, N Borodai, AM Botti, J Brack, I Brancus, T Bretz, A Bridgeman, FL Briechle, P Buchholz, A Bueno, S Buitink, M Buscemi, KS Caballero-Mora, B Caccianiga, L Caccianiga, M Candusso, L Caramete, R Caruso, A Castellina, G Cataldi, L Cazon, R Cester, AG Chavez, A Chiavassa, JA Chinellato, JCC Diaz, J Chudoba, RW Clay, R Colalillo, A Coleman, L Collica, MR Coluccia, R Conceicao, F Contreras, MJ Cooper, A Cordier, S Coutu, CE Covault, R Dallier, S D'Amico, B Daniel, S Dasso, K Daumiller, BR Dawson, RM de Almeida, SJ de Jong, G De Mauro, JRT de Mello Neto, I De Mitri, J de Oliveira, V de Souza, J Debatin, L del Peral, O Deligny, N Dhital, C Di Giulio, A Di Matteo, MLD Castro, F Diogo, C Dobrigkeit, W Docters, JC D'Olivo, A Dorofeev, RC dos Anjos, MT Dova, A Dundovic, J Ebr, R Engel, M Erdmann, M Erfani, CO Escobar, J Espadanal, A Etchegoyen, H Falcke, K Fang, G Farrar, AC Fauth, N Fazzini, AP Ferguson, B Fick, JM Figueira, A Filevich, A Filipi, O Fratu, MM Freire, T Fujii, A Fuster, F Gallo, B Garcia, D Garcia-Gamez, D Garcia-Pinto, F Gate, H Gemmeke, A Gherghel-Lascu, PL Ghia, U Giaccari, M Giammarchi, M Giller, D Glas, C Glaser, H Glass, G Golup, M Gomez Berisso, PF Gomez Vitale, N Gonzalez, B Gookin, J Gordon, A Gorgi, P Gorham, P Gouffon, N Griffith, AF Grillo, TD Grubb, F Guarino, GP Guedes, MR Hampel, P Hansen, D Harari, TA Harrison, JL Harton, Q Hasankiadeh, A Haungs, T Hebbeker, D Heck, P Heimann, AE Herve, GC Hill, C Hojvat, N Hollon, E Holt, P Homola, JR Hoerandel, P Horvath, M Hrabovsksy, T Huege, A Insolia, PG Isar, I Jandt, S Jansen, C Jarne, JA Johnsen, M Josebachuili, A Kaeaepae, O Kambeitz, KH Kampert, P Kasper, I Katkov, B Keilhauer, E Kemp, RM Kieckhafer, HO Klages, M Kleifges, J Kleinfeller, R Krause, N Krohm, D Kuempel, GK Mezek, N Kunka, AK Awad, D LaHurd, L Latronico, R Lauer, M Lauscher, P Lautridou, D Lebrun, P Lebrun, MA Leigui de Oliveira, A Letessier-Selvon, I Lhenry-Yvon, K Link, L Lopes, R Lopez, A Lopez Casado, A Lucero, M Malacari, M Mallamaci, D Mandat, P Mantsch, AG Mariazzi, V Marin, IC Maris, G Marsella, D Martello, H Martinez, OM Bravo, JJM Meza, HJ Mathes, S Mathys, J Matthews, JAJ Matthews, G Matthiae, D Maurizio, E Mayotte, PO Mazur, C Medina, G Medina-Tanco, VBB Mello, D Melo, A Menshikov, S Messina, MI Micheletti, L Middendorf, IA Minaya, L Miramonti, B Mitrica, L Molina-Bueno, S Mollerachl, F Montanet, C Morello, M Mostafa, CA Moura, G Mueller, MA Muller, S Mueller, I Naranjo, S Navas, P Necesal, L Nellen, A Nelles, J Neuser, PH Nguyen, M Niculescu-Oglinzanu, M Niechcio, L Niemietz, T Niggemann, D Nitz, D Nosek, V Novotny, H Nozka, LA Nunez, L Ochilo, F Oikonomou, A Olinto, N Pacheco, DP Selmi-Dei, M Palatka, J Pallotta, P Papenbreer, G Parente, A Parra, T Pau, M Pech, J Pekala, R Pelayo, J Pena-Rodriguez, IM Pepe, L Perrone, E Petermann, C Peters, S Petrera, J Phuntsok, R Piegaia, T Pierog, P Pieroni, M Pimenta, V Pirronello, M Platino, M Plum, C Porowski, RR Prado, P Privitera, M Prouza, EJ Quell, S Querchfeld, S Quinn, J Rautenberg, O Ravel, D Ravignani, D Reinert, B Revenu, J Ridky, M Risse, P Ristori, V Rizi, W Rodrigues de Carvalho, J Rodriguez Rojo, MD Rodriguez-Frias, D Rogozin, J Rosado, M Roth, E Roulet, AC Rovero, SJ Saffil, A Saftoiu, H Salazar, A Saleh, FS Greus, G Salina, JD Sanabria Gomez, F Sanchez, P Sanchez-Lucas, EM Santos, E Santos, F Sarazin, B Sarkar, R Sarmento, C Sarmiento-Cano, R Sato, C Scarso, M Schauer, V Scherini, H Schieler, D Schmidt, Scholtene, H Schoorlemmer, P Schovanek, FG Schroeder, A Schulz, J Schulz, J Schumacher, A Segreto, M Settimo, A Shadkam, RC Shellard, G Sigl, O Sima, A Smialkowski, R Smida, GR Snow, P Sommers, S Sonntag, J Sorokin, R Squartini, D Stanca, S Stanic, J Stapleton, J Stasielak, M Stephan, F Strafella, A Stutz, F Suarez, MS Duran, T Suomijarvi, AD Supanitsky, MS Sutherland, J Swain, Z Szadkowski, OA Taborda, A Tapia, A Tepe, VM Theodoro, C Timmermans, CJ Todero Peixoto, G Toma, L Tomankova, B Tome, A Tonachini, GT Elipe, D Torres Machado, P Travnicek, M Trini, R Ulrich, M Unger, M Urban, JFV Galicia, I Valino, L Valore, G van Aar, P van Bodegom, AM van den Berg, A van Vliet, E Varela, B Vargas Cardenas, G Varner, R Vasquez, JR Vazquez, RA Vazquez, D Veberic, V Verzi, J Vicha, M Videla, L Villasenor, S Vorobiov, H Wahlberg, O Wainberg, D Walz, AA Watson, M Weber, K Weidenhaupt, A Weindl, L Wiencke, H Wilczynski, T Winchen, D Wittkowski, B Wundheiler, S Wykes, L Yang, T Yapici, A Yushkov, E Zas, D Zavrtanik, M Zavrtanik, A Zepeda, B Zimmermann, M Ziolkowski, Z Zong, F Zuccarello, RU Abbasi, M Abe, T Abu-Zayyad, M Allen, R Azuma, E Barcikowski, JW Belz, DR Bergman, SA Blake, R Cady, MJ Chae, BG Cheon, J Chiba, M Chikawa, WR Cho, T Fujii, M Fukushima, T Gotoll, W Hanlon, Y Hayashi, N Hayashida, K Hibino, K Honda, D Ikeda, N Inoue, T Ishii, R Ishimori, H Ito, D Ivanov, CCH Jui, K Kadota, F Kakimoto, O Kalashev, K Kasahara, H Kawail, S Kawakami, S Kawana, K Kawata, E Kido, HB Kim, JH Kim, JH Kim, S Kitamura, Y Kitamura, V Kuzmin, YJ Kwon, J Lan, SI Lim, JP Lundquist, K Machida, K Martens, T Matsuda, T Matsuyama, JN Matthews, M Minamino, Y Mukai, I Myers, K Nagasawa, S Nagataki, T Nakamura, T Nonaka, A Nozato, S Ogioll, J Ogura, M Ohnishi, H Ohoka, K Oki, T Okuda, M Ono, A Oshima, S Ozawa, IH Park, MS Pshirkov, DC Rodriguez, G Rubtsov, D Ryu, H Sagawa, N Sakurai, LM Scott, PD Shah, F Shibata, T Shibata, H Shimodaira, BK Shins, HS Shin, JD Smith, P Sokolsky, RW Springer, BT Stokes, SR Stratton, TA Stroman, T Suzawa, M Takamura, M Takeda, R Takeishi, A Taketa, M Takita, Y Tameda, H Tanaka, K Tanaka, M Tanaka, SB Thomas, GB Thomson, P Tinyakov, I Tkachev, H Tokuno, T Tomida, S Troitsky, Y Tsunesada, K Tsutsumi, Y Uchihori, S Udo, F Urban, G Vasiloff, T Wong, R Yamane, H Yamaoka, K Yamazaki, J Yang, K Yashiro, Y Yoneda, S Yoshida, H Yoshii, R Zollinger, Z Zundel, I Collaboration, I Collaboration, PA Collaboration, PA Collaboration, TA Collaboration


Simulated stellar kinematics studies of high-redshift galaxies with the HARMONI Integral Field Spectrograph

Monthly Notices of the Royal Astronomical Society 458 (2016) 2405-2422

S Kendrew, S Zieleniewski, RCW Houghton, N Thatte, J Devriendt, M Tecza, F Clarke, K O'Brien, B Häußler

© 2016 The Authors.We present a study into the capabilities of integrated and spatially resolved integral field spectroscopy of galaxies at z = 2-4 with the future HARMONI spectrograph for the European Extremely Large Telescope (E-ELT) using the simulation pipeline, hsim. We focus particularly on the instrument's capabilities in stellar absorption line integral field spectroscopy, which will allow us to study the stellar kinematics and stellar population characteristics. Such measurements for star-forming and passive galaxies around the peak star formation era will provide a critical insight into the star formation, quenching and mass assembly history of high-z, and thus present-day galaxies. First, we perform a signal-to-noise study for passive galaxies at a range of stellar masses for z = 2-4, assuming different light profiles; for this population, we estimate that integrated stellar absorption line spectroscopy with HARMONI will be limited to galaxies with M* ≥ 1010.7 M⊙. Secondly, we use hsim to perform a mock observation of a typical star-forming 1010 M⊙ galaxy at z = 3 generated from the high-resolution cosmological simulation nutfb. We demonstrate that the input stellar kinematics of the simulated galaxy can be accurately recovered from the integrated spectrum in a 15-h observation, using common analysis tools. Whilst spatially resolved spectroscopy is likely to remain out of reach for this particular galaxy, we estimate HARMONI's performance limits in this regime from our findings. This study demonstrates how instrument simulators such as hsim can be used to quantify instrument performance and study observational biases on kinematics retrieval; and shows the potential of making observational predictions from cosmological simulation output data.


Constraints on Ultrahigh-Energy Cosmic-Ray Sources from a Search for Neutrinos above 10 PeV with IceCube.

Phys Rev Lett 117 (2016) 241101-

MG Aartsen, K Abraham, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, D Altmann, K Andeen, T Anderson, I Ansseau, G Anton, M Archinger, C Argüelles, J Auffenberg, S Axani, X Bai, SW Barwick, V Baum, R Bay, JJ Beatty, J Becker Tjus, KH Becker, S BenZvi, P Berghaus, D Berley, E Bernardini, A Bernhard, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, S Blot, C Bohm, M Börner, F Bos, D Bose, S Böser, O Botner, J Braun, L Brayeur, HP Bretz, A Burgman, T Carver, M Casier, E Cheung, D Chirkin, A Christov, K Clark, L Classen, S Coenders, GH Collin, JM Conrad, DF Cowen, R Cross, M Day, JP de André, C De Clercq, E Del Pino Rosendo, H Dembinski, S De Ridder, P Desiati, KD de Vries, G de Wasseige, M de With, T DeYoung, JC Díaz-Vélez, V di Lorenzo, H Dujmovic, JP Dumm, M Dunkman, B Eberhardt, T Ehrhardt, B Eichmann, P Eller, S Euler, PA Evenson, S Fahey, AR Fazely, J Feintzeig, J Felde, K Filimonov, C Finley, S Flis, CC Fösig, A Franckowiak, E Friedman, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, K Ghorbani, W Giang, L Gladstone, M Glagla, T Glüsenkamp, A Goldschmidt, G Golup, JG Gonzalez, D Grant, Z Griffith, C Haack, A Haj Ismail, A Hallgren, F Halzen, E Hansen, B Hansmann, T Hansmann, K Hanson, D Hebecker, D Heereman, K Helbing, R Hellauer, S Hickford, J Hignight, GC Hill, KD Hoffman, R Hoffmann, K Holzapfel, K Hoshina, F Huang, M Huber, K Hultqvist, S In, A Ishihara, E Jacobi, GS Japaridze, M Jeong, K Jero, BJ Jones, M Jurkovic, A Kappes, T Karg, A Karle, U Katz, M Kauer, A Keivani, JL Kelley, J Kemp, A Kheirandish, M Kim, T Kintscher, J Kiryluk, T Kittler, SR Klein, G Kohnen, R Koirala, H Kolanoski, R Konietz, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, K Krings, M Kroll, G Krückl, C Krüger, J Kunnen, S Kunwar, N Kurahashi, T Kuwabara, M Labare, JL Lanfranchi, MJ Larson, F Lauber, D Lennarz, M Lesiak-Bzdak, M Leuermann, J Leuner, L Lu, J Lünemann, J Madsen, G Maggi, KB Mahn, S Mancina, M Mandelartz, R Maruyama, K Mase, R Maunu, F McNally, K Meagher, M Medici, M Meier, A Meli, T Menne, G Merino, T Meures, S Miarecki, L Mohrmann, T Montaruli, M Moulai, R Nahnhauer, U Naumann, G Neer, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke Pollmann, A Olivas, A O'Murchadha, T Palczewski, H Pandya, DV Pankova, Ö Penek, JA Pepper, C Pérez de Los Heros, D Pieloth, E Pinat, PB Price, GT Przybylski, M Quinnan, C Raab, L Rädel, M Rameez, K Rawlins, R Reimann, B Relethford, M Relich, E Resconi, W Rhode, M Richman, B Riedel, S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, D Rysewyk, L Sabbatini, SE Sanchez Herrera, A Sandrock, J Sandroos, S Sarkar, K Satalecka, M Schimp, P Schlunder, T Schmidt, S Schoenen, S Schöneberg, L Schumacher, D Seckel, S Seunarine, D Soldin, M Song, GM Spiczak, C Spiering, M Stahlberg, T Stanev, A Stasik, A Steuer, T Stezelberger, RG Stokstad, A Stößl, R Ström, NL Strotjohann, GW Sullivan, M Sutherland, H Taavola, I Taboada, J Tatar, F Tenholt, S Ter-Antonyan, A Terliuk, G Tešić, S Tilav, PA Toale, MN Tobin, S Toscano, D Tosi, M Tselengidou, A Turcati, E Unger, M Usner, J Vandenbroucke, N van Eijndhoven, S Vanheule, M van Rossem, J van Santen, J Veenkamp, M Vehring, M Voge, M Vraeghe, C Walck, A Wallace, M Wallraff, N Wandkowsky, C Weaver, MJ Weiss, C Wendt, S Westerhoff, BJ Whelan, S Wickmann, K Wiebe, CH Wiebusch, L Wille, DR Williams, L Wills, M Wolf, TR Wood, E Woolsey, K Woschnagg, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, M Zoll, IceCube Collaboration

We report constraints on the sources of ultrahigh-energy cosmic rays (UHECRs) above 10^{9}  GeV, based on an analysis of seven years of IceCube data. This analysis efficiently selects very high- energy neutrino-induced events which have deposited energies from 5×10^{5}  GeV to above 10^{11}  GeV. Two neutrino-induced events with an estimated deposited energy of (2.6±0.3)×10^{6}  GeV, the highest neutrino energy observed so far, and (7.7±2.0)×10^{5}  GeV were detected. The atmospheric background-only hypothesis of detecting these events is rejected at 3.6σ. The hypothesis that the observed events are of cosmogenic origin is also rejected at >99% CL because of the limited deposited energy and the nonobservation of events at higher energy, while their observation is consistent with an astrophysical origin. Our limits on cosmogenic neutrino fluxes disfavor the UHECR sources having a cosmological evolution stronger than the star formation rate, e.g., active galactic nuclei and γ-ray bursts, assuming proton-dominated UHECRs. Constraints on UHECR sources including mixed and heavy UHECR compositions are obtained for models of neutrino production within UHECR sources. Our limit disfavors a significant part of parameter space for active galactic nuclei and new-born pulsar models. These limits on the ultrahigh-energy neutrino flux models are the most stringent to date.


The cosmic evolution of massive black holes in the Horizon-AGN simulation

Monthly Notices of the Royal Astronomical Society 460 (2016) 2979-2996

M Volonteri, Y Dubois, C Pichon, J Devriendt

© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.We analyse the demographics of black holes (BHs) in the large-volume cosmological hydrodynamical simulation Horizon-AGN. This simulation statistically models how much gas is accreted on to BHs, traces the energy deposited into their environment and, consequently, the back-reaction of the ambient medium on BH growth. The synthetic BHs reproduce a variety of observational constraints such as the redshift evolution of the BH mass density and the mass function. Strong self-regulation via AGN feedback, weak supernova feedback, and unresolved internal processes result in a tight BH-galaxy mass correlation. Starting at z ~ 2, tidal stripping creates a small population of BHs over-massive with respect to the halo. The fraction of galaxies hosting a central BH or an AGN increases with stellar mass. The AGN fraction agrees better with multi-wavelength studies, than single-wavelength ones, unless obscuration is taken into account. The most massive haloes present BH multiplicity, with additional BHs gained by ongoing or past mergers. In some cases, both a central and an off-centre AGN shine concurrently, producing a dual AGN. This dual AGN population dwindles with decreasing redshift, as found in observations. Specific accretion rate and Eddington ratio distributions are in good agreement with observational estimates. The BH population is dominated in turn by fast, slow, and very slow accretors, with transitions occurring at z = 3 and z = 2, respectively.


Scaling of up-down asymmetric turbulent momentum flux with poloidal shaping mode number in tokamaks

Plasma Physics and Controlled Fusion 58 (2016)

J Ball, FI Parra

© 2016 IOP Publishing Ltd.Breaking the up-down symmetry of tokamaks removes a constraint limiting intrinsic momentum transport, and hence toroidal rotation, to be small. Using gyrokinetic theory, we study the effect of different up-down asymmetric flux surface shapes on the turbulent transport of momentum. This is done by perturbatively expanding the gyrokinetic equation in large flux surface shaping mode number. It is found that the momentum flux generated by shaping that lacks mirror symmetry (which is necessarily up-down asymmetric) has a power law scaling with the shaping mode number. However, the momentum flux generated by mirror symmetric flux surface shaping (even if it is up-down asymmetric) decays exponentially with large shaping mode number. These scalings are consistent with nonlinear local gyrokinetic simulations and indicate that low mode number shaping effects (e.g. elongation, triangularity) are optimal for creating rotation. Additionally it suggests that breaking the mirror symmetry of flux surfaces may generate significantly more toroidal rotation.


Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

Monthly Notices of the Royal Astronomical Society 461 (2016) 2162-2173

SV Komarov, II Khabibullin, EM Churazov, AA Schekochihin

© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g. conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is ~0.1 per cent at energies ≳kT. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scales, which are impossible to resolve spatially. The absence of the effect at the predicted level may set a lower limit on the electron collisionality in the ICM. At the same time, the small value of the effect implies that it does not preclude the use of clusters as (unpolarized) calibration sources for X-ray polarimeters at this level of accuracy.


Thermal conduction in a mirror-unstable plasma

Monthly Notices of the Royal Astronomical Society 460 (2016) 467-477

SV Komarov, EM Churazov, MW Kunz, AA Schekochihin

© 2016 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society.The plasma of galaxy clusters is subject to firehose and mirror instabilities at scales of order the ion Larmor radius. The mirror instability generates fluctuations of magnetic-field strength δB/B ~ 1. These fluctuations act as magnetic traps for the heat-conducting electrons, suppressing their transport. We calculate the effective parallel thermal conductivity in the ICM in the presence of the mirror fluctuations for different stages of the evolution of the instability. The mirror fluctuations are limited in amplitude by the maximum and minimum values of the field strength, with no large deviations from the mean value. This key property leads to a finite suppression of thermal conduction at large scales. We find suppression down to ≈0.2 of the Spitzer value for the secular phase of the perturbations' growth, and ≈0.3 for their saturated phase. The effect operates in addition to other suppression mechanisms and independently of them. Globally, fluctuations δB/B ~ 1 can be present on much larger scales, of the order of the scale of turbulent motions. However, we do not expect large suppression of thermal conduction by these, because their scale is considerably larger than the collisional mean free path of the ICM electrons. The obtained suppression of thermal conduction by a factor of ~5 appears to be characteristic and potentially universal for a weakly collisional mirror-unstable plasma.


Age-velocity dispersion relations and heating histories in disc galaxies

Monthly Notices of the Royal Astronomical Society 462 (2016) 1697-1713

M Aumer, J Binney, R Schönrich

© 2016 The Authors.We analyse the heating of stellar discs by non-axisymmetric structures and giant molecular clouds (GMCs) in N-body simulations of growing disc galaxies. The analysis resolves long-standing discrepancies between models and data by demonstrating the importance of distinguishing between measured age-velocity dispersion relations (AVRs) and the heating histories of the stars that make up the AVR. We fit both AVRs and heating histories with formulae ∝tβ and determine the exponents βR and βz derived from in-plane and vertical AVRs and β~R and β~z from heating histories. Values of βz are in almost all simulations larger than values of β~z, whereas values of βR are similar to or mildly larger than values of β~R. Moreover, values of βz (β~z) are generally larger than values of βR (β~R). The dominant cause of these relations is the decline over the life of the disc in importance of GMCs as heating agents relative to spiral structure and the bar. We examine how age errors and biases in solar neighbourhood surveys influence the measured AVR: they tend to decrease β values by smearing out ages and thus measured dispersions. We compare AVRs and velocity ellipsoid shapes σz/σR from simulations to solar neighbourhood data. We conclude that for the expected disc mass and dark halo structure, combined GMC and spiral/bar heating can explain the AVR of the Galactic thin disc. Strong departures of the disc mass or the dark halo structure from expectation spoil fits to the data.


Characterizing stellar halo populations - I. An extended distribution function for halo K giants

Monthly Notices of the Royal Astronomical Society 460 (2016) 1725-1738

P Das, J Binney

© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.We fit an extended distribution function (EDF) to K giants in the Sloan Extension for Galactic Understanding and Exploration survey. These stars are detected to radii ~80 kpc and span a wide range in [Fe/H]. Our EDF, which depends on [Fe/H] in addition to actions, encodes the entanglement of metallicity with dynamics within the Galaxy's stellar halo. Our maximum-likelihood fit of the EDF to the data allows us to model the survey's selection function. The density profile of the K giants steepens with radius from a slope ~-2 to ~-4 at large radii. The halo's axis ratio increases with radius from 0.7 to almost unity. The metal-rich stars are more tightly confined in action space than the metal-poor stars and form a more flattened structure. A weak metallicity gradient ~-0.001 dex kpc-1, a small gradient in the dispersion in [Fe/H] of ~0.001 dex kpc-1, and a higher degree of radial anisotropy in metal-richer stars result. Lognormal components with peaks at ~-1.5 and ~-2.3 are required to capture the overall metallicity distribution, suggestive of the existence of two populations of K giants. The spherical anisotropy parameter varies between 0.3 in the inner halo to isotropic in the outer halo. If the Sagittarius stream is included, a very similar model is found but with a stronger degree of radial anisotropy throughout.


OBSERVATION and CHARACTERIZATION of A COSMIC MUON NEUTRINO FLUX from the NORTHERN HEMISPHERE USING SIX YEARS of ICECUBE DATA

Astrophysical Journal 833 (2016)

MG Aartsen, K Abraham, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, D Altmann, K Andeen, T Anderson, I Ansseau, G Anton, M Archinger, C Argüelles, J Auffenberg, S Axani, X Bai, SW Barwick, V Baum, R Bay, JJ Beatty, JB Tjus, KH Becker, S Benzvi, P Berghaus, D Berley, E Bernardini, A Bernhard, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, S Blot, C Bohm, M Börner, F Bos, D Bose, S Böser, O Botner, J Braun, L Brayeur, HP Bretz, A Burgman, T Carver, M Casier, E Cheung, D Chirkin, A Christov, K Clark, L Classen, S Coenders, GH Collin, JM Conrad, DF Cowen, R Cross, M Day, JPAMD André, CD Clercq, EDP Rosendo, H Dembinski, SD Ridder, P Desiati, KDD Vries, GD Wasseige, MD With, T Deyoung, JC Díaz-Vélez, VD Lorenzo, H Dujmovic, JP Dumm, M Dunkman, B Eberhardt, T Ehrhardt, B Eichmann, P Eller, S Euler, PA Evenson, S Fahey, AR Fazely, J Feintzeig, J Felde, K Filimonov, C Finley, S Flis, CC Fösig, A Franckowiak, E Friedman, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, K Ghorbani, W Giang, L Gladstone, M Glagla

© 2016. The American Astronomical Society. All rights reserved.The IceCube Collaboration has previously discovered a high-energy astrophysical neutrino flux using neutrino events with interaction vertices contained within the instrumented volume of the IceCube detector. We present a complementary measurement using charged current muon neutrino events where the interaction vertex can be outside this volume. As a consequence of the large muon range the effective area is significantly larger but the field of view is restricted to the Northern Hemisphere. IceCube data from 2009 through 2015 have been analyzed using a likelihood approach based on the reconstructed muon energy and zenith angle. At the highest neutrino energies between 194 TeV and 7.8 PeV a significant astrophysical contribution is observed, excluding a purely atmospheric origin of these events at 5.6s significance. The data are well described by an isotropic, unbroken power-law flux with a normalization at 100 TeV neutrino energy of (0.90 -0.27+0.30) × 10-18 Gev-1 cm-2 s-1 sr-1and a hard spectral index of γ = 2.13 ± 0.13. The observed spectrum is harder in comparison to previous IceCube analyses with lower energy thresholds which may indicate a break in the astrophysical neutrino spectrum of unknown origin. The highest-energy event observed has a reconstructed muon energy of (4.5 ± 1.2) PeV which implies a probability of less than 0.005% for this event to be of atmospheric origin. Analyzing the arrival directions of all events with reconstructed muon energies above 200 TeV no correlation with known γ-ray sources was found. Using the high statistics of atmospheric neutrinos we report the current best constraints on a prompt atmospheric muon neutrino flux originating from charmed meson decays which is below 1.06 in units of the flux normalization of the model in Enberg et al.


Marginal evidence for cosmic acceleration from Type Ia supernovae.

(2016)

JT Nielsen, A Guffanti, S Sarkar

The 'standard' model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present - as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these 'standardisable candles' indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.


Torus mapper: a code for dynamical models of galaxies

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 456 (2016) 1982-1998

J Binney, PJ McMillan


A review of action estimation methods for galactic dynamics

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 457 (2016) 2107-2121

JL Sanders, J Binney


Review of Particle Physics

Chin. Phys. C40 (2016) 10

C Patrignani, others


Sherlock et al. Reply:

Physical Review Letters 116 (2016)

M Sherlock, W Rozmus, EG Hill, SJ Rose


Searches for relativistic magnetic monopoles in IceCube

EUROPEAN PHYSICAL JOURNAL C 76 (2016) ARTN 133

MG Aartsen, K Abraham, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, D Altmann, T Anderson, I Ansseau, M Archinger, C Arguelles, TC Arlen, J Auffenberg, X Bai, SW Barwick, V Baum, R Bay, JJ Beatty, JB Tjus, K-H Becker, E Beiser, ML Benabderrahmane, P Berghaus, D Berley, E Bernardini, A Bernhard, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, C Bohm, M Boerner, F Bos, D Bose, S Boeser, O Botner, J Braun, L Brayeur, H-P Bretz, N Buzinsky, J Casey, M Casier, E Cheung, D Chirkin, A Christov, K Clark, L Classen, S Coenders, DF Cowen, AHC Silva, J Daughhetee, JC Davis, M Day, JPAM de Andre, C De Clercq, EDP Rosendo, H Dembinski, S De Ridder, P Desiati, KD de Vries, G de Wasseige, M de With, T DeYoung, JC Diaz-Velez, V di Lorenzo, JP Dumm, M Dunkman, B Eberhardt, T Ehrhardt, B Eichmann, S Euler, PA Evenson, S Fahey, AR Fazely, J Feintzeig, J Felde, K Filimonov, C Finley, T Fischer-Wasels, S Flis, C-C Foesig, T Fuchs, TK Gaisser, R Gaior, J Gallagher, L Gerhardt, K Ghorbani, D Gier, L Gladstone, M Glagla, T Gluesenkamp, A Goldschmidt, G Golup, JG Gonzalez, D Gora, D Grant, Z Griffith, A Gross, C Ha, C Haack, AH Ismail, A Hallgren, F Halzen, E Hansen, B Hansmann, K Hanson, D Hebecker, D Heereman, K Helbing, R Hellauer, S Hickford, J Hignight, GC Hill, KD Hoffman, R Hoffmann, K Holzapfel, A Homeier, K Hoshina, F Huang, M Huber, W Huelsnitz, PO Hulth, K Hultqvist, S In, A Ishihara, E Jacobi, GS Japaridze, M Jeong, K Jero, M Jurkovic, A Kappes, T Karg, A Karle, M Kauer, A Keivani, JL Kelley, J Kemp, A Kheirandish, J Kiryluk, J Klaes, SR Klein, G Kohnen, R Koirala, H Kolanoski, R Konietz, L Koepke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, K Krings, G Kroll, M Kroll, G Krueckl, J Kunnen, N Kurahashi, T Kuwabara, M Labare, JL Lanfranchi, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leuner, L Lu, J Luenemann, J Madsen, G Maggi, KBM Mahn, M Mandelartz, R Maruyama, K Mase, HS Matis, R Maunu, F McNally, K Meagher, M Medici, A Meli, T Menne, G Merino, T Meures, S Miarecki, E Middell, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, G Neer, H Niederhausen, SC Nowicki, DR Nygren, AO Pollmann, A Olivas, A Omairat, A O'Murchadha, T Palczewski, H Pandya, DV Pankova, L Paul, JA Pepper, CP de los Heros, C Pfendner, D Pieloth, E Pinat, J Posselt, PB Price, GT Przybylski, J Puetz, M Quinnan, C Raab, L Raedel, M Rameez, K Rawlins, R Reimann, M Relich, E Resconi, W Rhode, M Richman, S Richter, B Riedel, S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, L Sabbatini, H-G Sander, A Sandrock, J Sandroos, S Sarkar, K Schatto, F Scheriau, M Schimp, T Schmidt, M Schmitz, S Schoenen, S Schoeneberg, A Schoenwald, L Schulte, L Schumacher, D Seckel, S Seunarine, D Soldin, M Song, GM Spiczak, C Spiering, M Stahlberg, M Stamatikos, T Stanev, A Stasik, A Steuer, T Stezelberger, RG Stokstad, A Stoessl, R Strom, NL Strotjohann, GW Sullivan, M Sutherland, H Taavola, I Taboada, J Tatar, S Ter-Antonyan, A Terliuk, G Tesic, S Tilav, PA Toale, MN Tobin, S Toscano, D Tosi, M Tselengidou, A Turcati, E Unger, M Usner, S Vallecorsa, J Vandenbroucke, N van Eijndhoven, S Vanheule, J van Santen, J Veenkamp, M Vehring, M Voge, M Vraeghe, C Walck, A Wallace, M Wallraff, N Wandkowsky, C Weaver, C Wendt, S Westerhoff, BJ Whelan, K Wiebe, CH Wiebusch, L Wille, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, M Zoll


The XXL Survey: I. Scientific motivations - XMM-Newton observing plan - Follow-up observations and simulation programme

Astronomy and Astrophysics 592 (2016)

M Pierre, F Pacaud, C Adami, S Alis, B Altieri, N Baran, C Benoist, M Birkinshaw, A Bongiorno, MN Bremer, M Brusa, A Butler, P Ciliegi, L Chiappetti, N Clerc, PS Corasaniti, J Coupon, C De Breuck, J Democles, S Desai, J Delhaize, J Devriendt, Y Dubois, D Eckert, A Elyiv, S Ettori, A Evrard, L Faccioli, A Farahi, C Ferrari, F Finet, S Fotopoulou, N Fourmanoit, P Gandhi, F Gastaldello, R Gastaud, I Georgantopoulos, P Giles, L Guennou, V Guglielmo, C Horellou, K Husband, M Huynh, A Iovino, M Kilbinger, E Koulouridis, S Lavoie, AMC Le Brun, JP Le Fevre, C Lidman, M Lieu, CA Lin, A Mantz, BJ Maughan, S Maurogordato, IG McCarthy, S McGee, JB Melin, O Melnyk, F Menanteau, M Novak, S Paltani, M Plionis, BM Poggianti, D Pomarede, E Pompei, TJ Ponman, ME Ramos-Ceja, P Ranalli, D Rapetti, S Raychaudury, TH Reiprich, H Rottgering, E Rozo, E Rykoff, T Sadibekova, J Santos, JL Sauvageot, C Schimd, M Sereno, GP Smith, V Smolčić, S Snowden, D Spergel, S Stanford, J Surdej, P Valageas, A Valotti

© ESO, 2016.Context. The quest for the cosmological parameters that describe our universe continues to motivate the scientific community to undertake very large survey initiatives across the electromagnetic spectrum. Over the past two decades, the Chandra and XMM-Newton observatories have supported numerous studies of X-ray-selected clusters of galaxies, active galactic nuclei (AGNs), and the X-ray background. The present paper is the first in a series reporting results of the XXL-XMM survey; it comes at a time when the Planck mission results are being finalised. Aims. We present the XXL Survey, the largest XMM programme totaling some 6.9 Ms to date and involving an international consortium of roughly 100 members. The XXL Survey covers two extragalactic areas of 25 deg2 each at a point-source sensitivity of ∼5 × 10-15 erg s-1 cm-2 in the [0.5-2] keV band (completeness limit). The survey's main goals are to provide constraints on the dark energy equation of state from the space-time distribution of clusters of galaxies and to serve as a pathfinder for future, wide-area X-ray missions. We review science objectives, including cluster studies, AGN evolution, and large-scale structure, that are being conducted with the support of approximately 30 follow-up programmes. Methods. We describe the 542 XMM observations along with the associated multi-λ and numerical simulation programmes. We give a detailed account of the X-ray processing steps and describe innovative tools being developed for the cosmological analysis. Results. The paper provides a thorough evaluation of the X-ray data, including quality controls, photon statistics, exposure and background maps, and sky coverage. Source catalogue construction and multi-λ associations are briefly described. This material will be the basis for the calculation of the cluster and AGN selection functions, critical elements of the cosmological and science analyses. Conclusions. The XXL multi-λ data set will have a unique lasting legacy value for cosmological and extragalactic studies and will serve as a calibration resource for future dark energy studies with clusters and other X-ray selected sources. With the present article, we release the XMM XXL photon and smoothed images along with the corresponding exposure maps.


Search for astrophysical tau neutrinos in three years of IceCube data

PHYSICAL REVIEW D 93 (2016)

MG Aartsen, K Abraham, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, D Altmann, T Anderson, I Ansseau, M Archinger, C Arguelles, TC Arlen, J Auffenberg, X Bai, SW Barwick, V Baum, R Bay, JJ Beatty, JB Tjus, K-H Becker, E Beiser, S BenZvi, P Berghaus, D Berley, E Bernardini, A Bernhard, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, C Bohm, M Boerner, F Bos, D Bose, S Boeser, O Botner, J Braun, L Brayeur, H-P Bretz, N Buzinsky, J Casey, M Casier, E Cheung, D Chirkin, A Christov, K Clark, L Classen, S Coenders, DF Cowen, AHC Silva, J Daughhetee, JC Davis, M Day, JPAM de Andre, C De Clercq, EDP Rosendo, H Dembinski, S De Ridder, P Desiati, KD de Vries, G de Wasseige, M de With, T De Young, JC Diaz-Velez, V di Lorenzo, JP Dumm, M Dunkman, R Eagan, B Eberhardt, T Ehrhardt, B Eichmann, S Euler, PA Evenson, O Fadiran, S Fahey, AR Fazely, A Fedynitch, J Feintzeig, J Felde, K Filimonov, C Finley, T Fischer-Wasels, S Flis, C-C Foesig, T Fuchs, TK Gaisser, R Gaior, J Gallagher, L Gerhardt, K Ghorbani, D Gier, L Gladstone, M Glagla, T Gluesenkamp, A Goldschmidt, G Golup, JG Gonzalez, D Gora, D Grant, JC Groh, A Gross, C Ha, C Haack, AH Ismail, A Hallgren, F Halzen, E Hansen, B Hansmann, K Hanson, D Hebecker, D Heereman, K Helbing, R Hellauer, S Hickford, J Hignight, GC Hill, KD Hoffman, R Hoffmann, K Holzapfel, A Homeier, K Hoshina, F Huang, M Huber, W Huelsnitz, PO Hulth, K Hultqvist, S In, A Ishihara, E Jacobi, GS Japaridze, K Jero, M Jurkovic, A Kappes, T Karg, A Karle, M Kauer, A Keivani, JL Kelley, J Kemp, A Kheirandish, J Kiryluk, J Klaes, SR Klein, G Kohnen, R Koirala, H Kolanoski, R Konietz, L Koepke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, K Krings, G Kroll, M Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, JL Lanfranchi, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leuner, L Lu, J Luenemann, J Madsen, G Maggi, KBM Mahn, R Maruyama, K Mase, HS Matis, R Maunu, F McNally, K Meagher, M Medici, A Meli, T Menne, G Merino, T Meures, S Miarecki, E Middell, E Middlemas, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, G Neer, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, A Olivas, A Omairat, A O'Murchadha, T Palczewski, H Pandya, DV Pankova, L Paul, CPDL Heros, C Pfendner, D Pieloth, E Pinat, J Posselt, PB Price, GT Przybylski, J Puetz, M Quinnan, C Raab, L Raedel, M Rameez, K Rawlins, R Reimann, M Relich, E Resconi, W Rhode, M Richman, S Richter, B Riedel, S Robertson, M Rongen, C Rott, T Ruhe, D Ryckbosch, SM Saba, L Sabbatini, H-G Sander, A Sandrock, J Sandroos, S Sarkar, K Schatto, F Scheriau, M Schimp, T Schmidt, M Schmitz, S Schoenen, S Schoeneberg, A Schoenwald, L Schulte, D Seckel, S Seunarine, MWE Smith, D Soldin, M Song, GM Spiczak, C Spiering, M Stahlberg, M Stamatikos, T Stanev, NA Stanisha, A Stasik, T Stezelberger, RG Stokstad, A Stoessl, R Stroem, NL Strotjohann, GW Sullivan, M Sutherland, H Taavola, I Taboada, J Tatar, S Ter-Antonyan, A Terliuk, G Tesic, S Tilav, PA Toale, MN Tobin, S Toscano, D Tosi, M Tselengidou, A Turcati, E Unger, M Usner, S Vallecorsa, J Vandenbroucke, N van Eijndhoven, S Vanheule, J van Santen, J Veenkamp, M Vehring, M Voge, M Vraeghe, C Walck, A Wallace, M Wallraff, N Wandkowsky, C Weaver, C Wendt, S Westerhoff, BJ Whelan, N Whitehorn, K Wiebe, CH Wiebusch, L Wille, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, DL Xu, XW Xu, Y Xu, JP Yanez, G Yodh, S Yoshida, M Zoll, I Collaboration


The violent white dwarf merger scenario for the progenitors of Type Ia supernovae

Monthly Notices of the Royal Astronomical Society 461 (2016) 3653-3662

DD Liu, B Wang, P Podsiadlowski, Z Han

© 2016 The Authors.Recent observations suggest that some Type Ia supernovae (SNe Ia) originate from the merging of two carbon-oxygen white dwarfs (CO WDs). Meanwhile, recent hydrodynamical simulations have indicated that the accretion-induced collapse may be avoided under certain conditions when double WDs merge violently. However, the properties of SNe Ia from this violent merger scenario are highly dependent on a particular mass-accretion stage, the so-called WD + He subgiant channel, during which the primary WD is able to increase its mass by accreting He-rich material from an He subgiant before the systems evolves into a doubleWD system. In this paper, we aim to study this particular evolutionary stage systematically and give the properties of violentWDmergers. By employing the Eggleton stellar evolution code, we followed a large number of binary calculations and obtained the regions in parameter space for producing violent mergers based on the WD + He subgiant channel. According to these simulations, we found that the primary WDs can increase their mass by ∼0.10-0.45M⊙ during the massaccretion stage. We then conducted a series of binary population synthesis calculations and found that the Galactic SN Ia birthrate from this channel is about 0.01-0.4 × 10-3 yr-1. This suggests that the violent WD mergers from this channel may only contribute to ∼0.3-10 per cent of all SNe Ia in our Galaxy. The delay times of violent WD mergers from this channel are ≥1.7Gyr, contributing to the SNe Ia in old populations. We also found that the WD + He subgiant channel is the dominant way for producing violent WD mergers that may be able to eventually explode as SNe Ia.